Declining battery health is a manageable and normal part of maintenance costs of electric vehicles 1-Click Survey #13

Your take-home messages:

Declining battery health is a worry for some electric vehicle owners, especially those with small and early EV models. Others are unfazed by it and expect battery refurbishment to become a normal and manageable part of maintenance and repairs. Cost of battery refurbishment does not compromise the net positive life-time value proposition of owning an electric car or plug-in hybrid instead of a combustion vehicle.

To provide context, the proposition was prefaced by the following statement: “The range, utility and long-term value of an electric or plug-in hybrid vehicle may in part depend on its battery’s ‘Sate of Health’ i.e. how much energy the battery can hold when fully charged compared to when it was first manufactured. We want to know whether the decline in battery State of Health as the vehicle ages is a problem.”

Participants could choose between the following five options:

(1) Strongly agree

(2) Agree

(3) Neither agree nor disagree

(4) Disagree

(5) Strongly disagree

The poll was sent on 14 November 2017 to 399 EV owners and 41 PHEV/REX owners who have enrolled in the Flip the Fleet project • 227 EV and 18 PHEV/REX owners responded by 21 November • 129 respondents provided reasons for their choice.

Your scores

The results were more evenly spread across the spectrum than any of the 1-click surveys conducted by Flip the Fleet to date. Forty-nine percent of respondents either ‘strongly agreed’ or ‘agreed’ that battery health significantly impacts (Fig. 1), and 28% ‘disagreed’ or ‘strongly disagreed’. This left a high proportion (23%) of EV owners who neither agreed or disagreed with the proposition.

Fig.1 Responses of 227 EV and 18 PHEV/REX owners to the proposition that “Declining battery ‘State of Health’ significantly impacts on the practicality and lifetime value proposition of owning an electric or plug-in hybrid vehicle”

What makes you Click?

The overarching conclusion of NZ EV owners who responded to this survey is that the importance of battery capacity degradation depends entirely on context – if a reduced range still meets an owner’s needs, there is no problem. People with the earlier model EVs and a small battery are the most vulnerable and there may come a time when they have to sell the EV or invest in refurbishing or replacing the battery pack. For many others, even ones with entry-level models, the observed rate of battery capacity decline is perfectly acceptable. PHEV owners may be less concerned about the impact of degradation on electric range because they have the back-up of an onboard ICE, but the limited ‘electric range’ of a PHEV still reduces their longer-term economic value proposition. Many respondents urged prospective buyers to build some allowance for battery replacement into their expected return on investment and depreciation calculations – battery refurbishment is just a normal part of repairs and maintenance of EVs and PHEVs, and in the longer run will probably be more than compensated for by reduced fuelling and other repairs and maintenance that are incurred by ICE vehicles. The cost of battery refurbishment or replacement is the main uncertainty in the long-term value proposition, but it is expected to be well below the cumulative savings captured by EVs and PHEVs.

An urgent national priority is to develop a battery replacement and refurbishment industry, partly to build confidence of prospective buyers but also to support early adopters of smaller EVs. Cost and batteries is falling fast and their longevity is increasing, so this the impact on the practicality and life-time value proposition of EVs and PHEVs is steadily reducing. There is huge variation in the rate of battery degradation, and considerable debate about what causes this. Finding out why might help people reduce the rate of degradation and guide education programmes.

Overall, respondents identified battery capacity decline as an important issue to be tracked and built into longer term expectations. But it is not a deal breaker.

Research Priorities & Recommendations:

This survey illustrates the need for further research to develop and communicate:

Clearer information on the feasibility and costs of battery refurbishment

Improved metrics of battery State of Health and what causes its short-term fluctuations

More precise measures of the average rate of decline in battery capacity of different models

Understanding of what causes the large variation in rates of decline in battery capacity being observed between EVs of the same model and age, so that we can learn how to minimise it in future

Case studies of battery refurbishment or replacement, and the potential repurposing of the batteries in the long term.

Our main recommendation is for urgent and substantive investment in building an EV battery refurbishment, replacement and repurposing industry throughout New Zealand. We also plea that more EV owners join Flip the Fleet and start contributing battery State of Health metrics so the battery degradation issues are better understood and anxiety among prospective EV purchasers can be reduced.

Your comments in detail:

Below is a lightly edited and re-arranged record of all the comments received. Around 20 commentaries have been left out because their content had been covered by contributions recorded below

It’s all about appropriate range again: “Range, range, range” ● “While I do see this as a problem (especially in terms of resale value) it shouldn’t affect me personally. As the vehicle is used primarily for short distances/commuting, it won’t be until 25-30% of the original range where it will start to affect my commuting (and even then, not necessarily as I could still utilize the growing fast charger network)” ● “So many factors that I couldn’t answer strongly in either direction. Most people will consider SoH when buying, but practically it is not affecting my ownership or satisfaction or the way I use my EV. If travelling close to the available range then it becomes important but most people don’t” ● “At 79% battery state-of-health our Leaf’s range is limited to about 100km for a trip that includes some highway & hills. For any trip longer than this we either need to charge part-way or use our petrol car. We’ll have to work out the threshold SOH at which we think about replacing the battery” ● “This question invokes the ‘range anxiety’ concept, which as we all know disappears very quickly once a driver understands their particular car” ● “If you have ever owned an electric forklift you will know that even stuffed batteries will hold an amount of charge till they totally short out. So you may not get the maximum range for the car batteries whole life, but if it holds sufficient charge to get to and from work lets say, it is still a viable means of transport”

Restricted range still good enough for many users: “The answer lies in the use case. For many people it won’t matter. For others, who require a certain level of battery capacity, it will be the only thing that matters” ● “I drive 40km on average or so a day. The maximum distance I have had to drive to a rapid charger is 30km, and maximum travel ever 80km. So even an older Gen1 Leaf is fine for a long time” ● “Our leaf is used as an around town car. It’s battery state of health is 92% but it could get a lot lower and we’d still get strong value from it with an overnight charge, and charging during trips would probably extend its utility at that state of health. A trip into town and back generally uses 22% of the battery’s charge” ● “Even after the battery goes down below 70%, it is still in a usable state – just that the range is reduced” ● ” Most of us drive nowhere near the range offered, and so on a day to day basis there is no problem” ● “Your question was worded with ‘significantly’. I would say the impact of degradation is quite minor, so I answered ‘disagree’” ● “The value of a vehicle is only a function of how it meets my needs – which is getting a to b and back again. Right now my 2011 Leaf will do about 80km – so I limit journeys to less than this (or use another vehicle). In 3 years will I only get 60 km? In 5 years, will it be 40km?” ● “My Leaf’s State of Health is now 78%. I am not concerned about the distance it will travel because as yet I haven’t noticed that reduce” ● “If you are buying an EV for around town, short trips etc and buying an older model to save $$ or because that’s all you can afford, there’s no problem at all. If you can afford a new higher spec model it will have a greater range and be a LONG time before the SOH is too low” ● “95 per cent of my journeys are around 26km. Reduced battery range would have little effect on my ability to use the car” ● “The downside to this Flip the Fleet thing is that everyone thinks they are a battery expert. If your car is down to 10 bars or 9 bars and you only ever do 40KM in a day, what’s the problem? My early 2012 has still got 87%soc and 12 Bars. 25000KM. I’ve seen the same year car with 20000km with a SOH of 76%. Even at that SOC it still suites the owner fine for his 60Km commute” ● “Two reasons, first with a current (~4yrs old) battery only range of 40-45km, my PHEV would have to drop very significantly to below 30km before it is operation in typical daily use is significantly impacted. Second, I’m expecting that in the time frame it takes for the range to drop replacement battery technologies are likely to improve to double the capacity, which would be very worthwhile & that the old battery will still be perfectly viable as part of a home solar PV installation” ● “I bought my EV to be able to do a 30km round trip commute to work. I can currently charge “for a limited time” for free at work and I also have a fast charger halfway between work and home. So, a declining SoH of my Leaf battery doesn’t concern me as long as I can do my 30km round trip commute, even on a cold day in the middle of winter when the battery isn’t as efficient” ● “even if range eventually declines to 50% it would still be sufficient for more than 90% of our vehicle needs. Typically, we are only charging twice a week (at night) at present, so a 50% drop in range would just mean charging four nights a week – not a problem”

A uniquely EV and new issue: “The state of health is a factor that only affects EVs – and so is going to be a factor in the viability of an EV for many people. Balanced against this is the likelihood of replacement batteries and the fact that many don’t need a huge amount of range for their commute” ● “If your Battery fails it’s like running out of petrol and the petrol stations have shut down. Or your engine broke down and you need a replacement engine with high costs. Or if it holds less and less power, it seems like your petrol tank has a leak and you are losing petrol and km range. The Battery is just vital for an electric vehicle” ● “All things degrade over time, but it would have to be a concern over the ‘extent’ to which a SOH value decreases. If the quality is right, then should be no issue. If something is manufactured badly, and SOH suffers as a result, then the EV won’t stack up as well versus a very well made non-EV”

Restricted range will be a problem for some owners and businesses: “If the range is cut down it does limit the usability for us as a business” ● “Declining state of health = can’t drive as far = less useful vehicle” ● “SoH = EV range. Low(er) SoH = Low(er) range” ● “Declining SOH will affect range which for us is a mayor limitation of EV” ● “If I currently want to drive (for whatever reason) non-stop to Taupo from Cambridge, my LEAF can *just* do it. If the battery declines by even 5%, I would find I need to slow down so much it would no longer be viable” ● “It would be the same as a shrinking fuel tank in a car, it simply gets to a point where it is not feasible” ● “Our Nissan Leaf is our sole family/household car, so used for all our trips. As SOH reduces so does the effective range (obviously), so our travel options are affected (although mitigated by increase in road-side/public chargers)”

Degradation rate varies a lot between models: “Tesla Model S Batteries are indicating a SOH battery decline of around 5% per 10 years. Nissan Leaf batteries are around 30% per 10 years. This is a significant difference in terms of purchasing choice and resale value of the vehicle as different manufacturers adopt different battery technologies”

More of an issue for early and smaller EVs: “I think this issue is more with the Gen 1 Leaf. Personally, I used to be able to drive home and back to work again (approx. 100kms) in my 2011 LEAF. Now the battery has declined to 75% SOH meaning I have to charge at both home and work. Still a perfectly valid town car and far, far cheaper to run than an ICE for me, but it severely limits my range. I can’t get to Tauranga or Rotorua (from Whakatane) for example, so we have to use our other ICE car” ● “With the exception of Gen 1 Leafs, SoH doesn’t seem to be limiting or significantly affecting the range of EVs across manufacturers as cars age” ● “If low SOH on a huge battery still means 200km range then no big deal. If it suggests a 60-80km range then the car will be an expensive paperweight for many people” ● “Current Battery sizes are small and vehicle ranges are low. A small reduction in battery capacity has a large impact on the usefulness of the vehicle” ● “Those with smaller batteries and earlier batteries will have most concern about SoH and its impact on resale value. The Nissan Leaf has done the heavy lifting to get EVs on the road, but inevitably the 2011 and 2012 Gen 1s will carry the burden of early adoption – some Gen 1s at 70% SoH are going to need a replacement or restored battery within 10 years if they are to be practical for most owners. But these smaller cars are also cheaper and we have benefited from the government subsidies paid overseas”

An important issue for PHEV cost-effectiveness …: “I have had my plug-in hybrid Mitsubishi for too short a time to answer this sensibly. The range of my car’s battery is short anyway. If it declines noticeably over the first year or two, I would be very disappointed. However, the battery is covered by an 8-year warranty” ● “Unfortunately I’m seeing the battery performance in our Mitsubishi Outlander reducing after 3 years – it was already less than the advertised capacity at time of purchase (about 35 km instead of the advertised 50 km) – although this it has been adequate for the commute to and from work. Given the premium that we paid for the PHEV Outlander , I suspect the value proposition is questionable – the technology still needs to improve and the price point needs to come down to really drive the transition to an electric fleet” ● “The impact might be greater for the Plugin Hybrids which typically have very small batteries – sure, you are not going to get stuck because you have the back-up of the ICE motor, but the cost effectiveness of a PHEV is definitely going to drop as the battery SoH declines and you are forced back onto petrol even for a lot of your local running”

… but reducing range itself is less of an issue for a PHEV: “As a Nissan LEAF I have only a (say) 125 km range anyway, so I would be greatly disadvantaged by a drop of (SAY) just 10% and I would begrudge having to have the cost of a battery change. HOWEVER, if I had a Plugin Hybrid, I would probably be happy to “make do” until my batteries were only operating at (say) 50%.

Less of an issue for new long-range EVs: “Having an early battery that declines by 4% per year is a sore point. As range of new models gets larger, the deterioration will mean less” ● “More notable to me, than slight reduction in range, is the massive increase in range of new vehicles coming onto the market. My car going from 110km to 105km range, is nothing compared to the new 40kWh Nissan Leaf going 200-300km! #envy!”

Little degradation visible for some EVs: “I haven’t noticed any degradation in the 2.5 years that I have had the car” ● “I haven’t seen a real-world loss of range yet despite what seems to be a 3-4% drop in SOH from when I purchased it” ● “Our Leaf has lost around 4% SoH in two and a half years – if that keeps up I’ll be able to use it effectively for 30-40 years before we cannot take it on our main regular trip of 47 km. The key issue is whether the battery will suddenly tip-over in the future, and if so, when. If you own a Tesla with its superior technology (and temperature controlled battery) – it’s not going to be a serious problem for way over 50 years, even in very long trips”

Rate of degradation is acceptable for many owners: “The rate of deterioration averaging around 4-5% a year means I am unlikely to be significantly affected by SOH until another decade – and I strongly believe that before then a range of options will be available to repair or replace the batteries” ● “Basically my Outlander is a four-year-old import. The range unit now is still 44 to 46 km per charge. While a new one does fifty km, so they say” ● “Bit of a no brainer really. Like having to pay taxes affects the amount you can spend on stuff you want” ● “The decline in SoH is reasonably slow, so should not become a significant problem for many years. The battery still has value even when depleted too much to be useful in the EV. I have heard it said that ‘the life of the battery is the life of the car’, but that does sound a bit optimistic, depending how often people like to renew their cars” ● “I’ve now owned my 2014 BMW i3 for just on three years, and driven about 55000km. In that time, the car’s range may have dropped off very slightly, maybe 10 or 20 km. When I bought it new, fully charged and using the range extender as well gave me a range of about 320 km. That’s now about 300 km. I am more than happy with that” ● “My Tesla apparently will retain over 90% of its battery capacity after 220,000 Km!”

Battery health is an important consideration when buying: “Now that I know about it, I would check it on any second hand EV that I was buying. When I bought my Leaf with 7500 km, I assumed, without thinking, that the battery would be Ok. Thankfully it is. Soon Flip the Fleet will be able to relate SOH to age and km. Eventually it should be part of the standard information a seller needed to supply” ● “I agree that you have to factor this in when buying an EV and dealing with your range anxiety, but I wouldn’t say that is has a significant impact. If the question had been phrased without the word “significantly” I’d have answered “Agree” [respondent scored 3 – Neither agree nor disagree] ● “The only time the Health of the battery is important is when buying the car so you know the dealer isn’t trying to rip you off” ● “It is usually the first question a prospect buyer will ask” ● “People spend a lot of money of EVs, they need to know that that investment will be worth it over the lifetime of the vehicle. If that lifetime is short due to poor SOH, then that makes the investment problematic. It was only by reading up about the SOH before we bought that made me confident we wouldn’t be buying a Lemon” ● “SoH is the most important factor when buying an electric vehicle, in order to get maximum range. Therefore, I would expect the on-selling of a vehicle with a poorer SoH to attract a lower price, than one with a higher SoH” ● “Battery health is an important added variable for owners and prospective buyers to get their head round – they need to be less concerned about the odometer reading or age of the vehicle than for an ICE vehicle” ● “As it is general knowledge that the batteries deteriorate as they age, it would be reasonable to assume people would take this into account when purchasing an electric vehicle. Even after a few years though the range will still be more than the average daily commute” ● “The effect of battery decline depends strongly on each person’s circumstances – i.e. whether the car had ample range for their needs to begin with. It should definitely be taken into account when deciding what kind of vehicle to buy”

Treat SoH as a consumable and build it into depreciation and lifetime cost analysis: “Batteries are a major part of the initial cost and like a laptop battery, could be considered a consumable. For the Nissan Leaf 2011 it appears that reducing battery capacity will be an ongoing major factor in depreciation” ● “SOH impacts on the whole of life cost of the vehicle, resale value will be also affected” ● “Remember back when car engines only lasted 100,000 miles – some of them like the Leyland 1300 only lasted 40,000 miles” ● “It does need factoring in if you intend to keep the car a long time, eg. an ICE will continue to operate basically for 15-20 years if you service it and repair it as you go. It is unlikely a battery vehicle will have much range after that amount of time due to battery degradation” ● “The key to fuel cost efficiency is not simply a matter of the relative prices of electricity and petrol, but also includes the storage capacity and lifespan of the battery” ● “Battery degradation is now well understood – so should be understood and factored into initial and subsequent purchase price” ● “The ‘lifetime value proposition’ will vary person to person as everyone has different ideas about how long to keep a car”

Resale value a concern: “I am concerned about the resale value which seems to have fallen through the floor!!” ● “Resale value will always be about perception of remaining life” ● “Car values plummet at 100,000 km, and as the market grows more knowledgeable about EVs they will ask questions about SOH” ● “Today a 10-Bar leaf should be around $10,000, not $13,000” ● “Degraded battery definitely reduces the value of the vehicle… At the same time, most people’s daily commute can be done even with a 50% degraded battery” ● “For a Gen1 Nissan leaf with <100km range there will come a time when it is difficult to resell because the potential buyer will consider the range is not enough, so it is important. Even for a longer-range car of 200km, after 10 years with a new max range of 150km, it will be impact on resale. For a Tesla at > 400km range the impact may not be felt for 15 years – it isn’t such a big deal in that case”

There will always be buyers of short range EVs: “There will always be someone with a lower-range requirement to buy it off you” ● “As my own confidence in the ability of my car grows the SoH is just another thing to consider… For some a 24kw car with 65% SoH will be fine… if price is right” ● “While a decline in battery capacity will have an impact on how I use my car, I’m hoping that by the time this happens I will be able to upgrade. There will still be a market for cars that have lost capacity with people who only drive short distances between charging opportunities. Things are changing so fast that in a few years there will be options for everybody to either restore range to their cars or change to one that still meets their needs” ● “I guess when my cap goes down there’s a market for shorter distance metro runabouts, I can sell too and upgrade. No problem” ● “The reduced range of older vehicles will be best handled by passing the vehicle onto new owners who have the drive cycle to match the vehicle. This is already the case for ICE vehicles – V8s are left at home during the week – but come out for weekends; with more economic vehicles used for commuting trips. Many vehicles in NZ are used for short tripping e.g. the car to the train station. Perfect use for aging EVs”

Save to replace the battery when necessary: “Remaining capacity of the battery impacts on trade in or resale value of the vehicle and is therefore a cost per kilometre over and above the small electricity cost. This is the reason why I am putting aside my equivalent petrol saving for future battery replacement or to make up depreciation when I replace my EV”

Even if you have to replace a battery, EVs still make financial sense: “By the time the battery degrades significantly enough, we would have already made a lot savings in terms of CO2 emissions and reduced fuel costs” ● “For high-mileage users, the fuel savings easily outweigh any battery depreciation. For lower-mileage users, not so much” ● “It has an impact simply because if it didn’t change over time, it would hold its range and charge forever. But the impacts are readily manageable and well within the value proposition. The batteries deteriorate over use but they can be refurbished or replaced and total cost of ownership is still on the positive” ● “I do not change vehicles regularly, and as I am not planning on selling the car for at least another 5 years (provided the battery performs well enough for day-day use) the amount of money saved through not buying petrol will likely have paid for the car, or at least the associated depreciation” ● “I think SOH is an issue over the lifetime of a car, which is why I initially went with agree. But in terms of the lifetime value proposition, I disagree that it is a significant issue. i.e. Yes, if you want to have the car for many years the battery will probably need to be replaced. But, given the amount of money saved compared to petrol, an EV is still a valuable proposition overall from an economic point of view” ● “Its so insignificant decrease per year 3-5% by the time the car is 5 YO we replace for company deprecation” ● “The cost of a replacement battery pack needs to be factored into the decision to purchase an EV, however it won’t take too many years for the savings in fuel and running costs to cover the cost of a replacement battery and the battery should last a good many years past that point. Also, over the life of an ICE powered vehicle I suspect that the maintenance costs will far outstrip the costs of a replacement battery for an EV” ● “even if you got the ball rolling by buying a small early EV and so have to replace or refurbish the battery occasionally during its life time, that’s not a big expense compared to the costs in maintenance and petrol that you’ve dodged along the way”

Not a deal breaker: “Declining SOH is certainly something to be aware of but it’s not a deal-breaker. When my car’s range is no longer practical I’m confident I’ll be able to replace the battery at a reasonable price, or buy another car” ● “I think we all know to expect a slow decline in the battery SOH and that this is nothing to get too excited about” ● “Slowly getting worse but not an issue compared to all the other benefits” ● “Degradation of battery SoH is a very minor issue when considering purchasing an EV today” ● “I purchased my iMiEV accepting that over the medium/long term time this possible negative might be an issue but it’s certainly no game changer and no big concern to me” ● “The upsides to EV ownership out way this concern” ● “Loss of SOH impacts range and therefore the practicality of the EV so its usefulness/worth decreases. Reduced SOH is however not the end of the world and just needs a bit more careful management to reduce its impact” ● “The effect on the future resale value of the vehicle is uncertain, but is not a big deal for early adopters when compared with other risk factors such as evolving technology and consequently reducing entry costs”

The future is still uncertain: “We don’t know (yet) how long the batteries will last. Tesla batteries appear to have a long life – 300,000 km. Prius batteries similar Leaf batteries?? – not so sure” ● “The technology is definitely there for the battery NOT to be a worry but have all of the manufacturer’s cracked it?” ● “To be honest, I just don’t know” ● “Who knows, in 5 years’ time Nissan New Zealand might actually start support New Zealand LEAF owners (for a change) and enable new battery replacement, or other ‘after-market’ battery replacement options may become available” ● “Battery capacity directly affects range so previously attainable travel legs would no longer be viable. Also, more frequent re charging would be necessary, increasing travel time. Resale value of vehicle would be reduced the same as a petrol vehicle with high Km (increased engine wear). After time lowered battery capacity would restrict the vehicle to local running. I do not see this as a critical issue since existing vehicles have similar problems, the question would be when does the vehicle arrive at this state, if it’s after 8 years then financially it would be a problem, but if it was 15 years then it would be acceptable” ● “Electric has been around for a long time but the general public have not had an opportunity to domestically use EVs, so the anxiety around a battery failing is very real still. Until we experience solving a problem battery, we can’t know for sure if the cost and hassle is less than a combustion engine. I personally envisage that an EV is far more economical in $ and time in comparison to a combustion engine. The more resources we have access to in the community for maintenance and ongoing running of EVs, the better it will become for owners” ● “Not knowing how rapid the decline is a problem. If we knew how quickly the battery will degrade over time, and exactly how that will affect range in km, we could include those figures when making our decision to buy the car. It’s the uncertainty about how much, not the fact of decline which is a problem. And you folk are well on the way to sorting out those numbers for us. Thank You!”

Will new replacement batteries be manufactured? “My worry is, not the cost of replacing the battery when needed, but how long will the manufacturer continue to make batteries for the car, as with Nissan, each model has a new battery, and they are not backwards compatible – I can’t see them making “old technology” batteries, they will want us to buy new cars – thus limiting the lifespan of the car and its value. That being said, I still LOVE my EV and have no regrets buying it”

A lot depends on Nissan: “I think it’s important to be realistic about the expected life of a battery, especially since currently in NZ there is uncertainty about what happens with the Nissan Leaf when the battery needs to be replaced. I’d be more comfortable if some reputable agency took this on, since it appears that Nissan NZ ironically disowns “their” biggest selling electric car”

An urgent need to develop battery refurbishment industry: “NZ urgently needs to build the businesses and know-how to service, refurbish, replace and recycle the older batteries for these earlier vehicles. This is needed mainly to build confidence amongst buyers that their resale value will hold up” ● “Battery health impacts resale value directly and as yet there are no viable battery replacement options in NZ. Therefore, a well maintained and mechanically viable EV is destined for disposal purely because the battery is no longer within say 20% of what is was when it was new. Equally newer EV’s will have been released with improved capacity and chemistry” ● “So unless I can get a viable replacement battery, the value of the vehicle has dropped considerably” ● “In any event there is always a deterioration, but like the batteries in anything once they’ve expired I will replace them and the range on the car will be like new again – maybe even better!” ● “I have a Gen 1 Leaf 2011 model. Cost $20,000 in Jan 2016 when I didn’t know anything about battery health. Now down to 9 bars and about 72% SOH and value dropped to less than $10,000. It is now really only useful as a commuting car with a city range of 80k but considerably less on open road. I have done about 18,000 km. therefore it has cost me $0.55 per km in depreciation. The car is still in tip top condition. It is lovely to drive and could last for many years if the battery could be renewed or upgraded. I think it is critical to find a way to renew batteries at a reasonable cost, otherwise we will be trashing cars with years of life left in all parts except the battery” ● “I’m banking on the practical demand for cell-level battery replacement for Nissan Leaf cars being available in NZ sometime in the next 5 years. Periodically (every few years) replacing only the cells that require it should add many years of life to the battery pack and the car, without breaking the bank” ● “We haven’t had any problem with declining battery health yet. But once it starts happening, it would be nice to be able to change to a new battery. In nelson, currently there is no service, so it would be great that these maintenance services could be provided all over NZ for EV owners”

Battery degradation adds fuelling cost: “Relative ‘fuel’ costs are often quoted on the assumption that the EV owner will make use of the lower night-time electricity costs. Battery degradation makes that less likely, especially for those people that live out of town and have longer drives to get to the shops, their neighbours or leisure activities”

Need for certainty about battery replacement options and costs: “More certainty about the methods, cost and ease of battery replacement would help alleviate this concern. At the moment, battery replacement is a theoretical consideration – hardly anyone in NZ has actually done it. A case study on a real battery replacement job would be a really good thing to have and circulate” ● “I could neither agree nor disagree because I feel that there are other facts that are needed to make a reasonable decision; such as whether or not replacement batteries are available and at what cost” ● “The main issue, though, is how fast the batteries are declining. If when the car was say three years old, the batteries began to gently decline, say a bar a year, then we could live with that for a few years. By then, hopefully, there will be more people around like Blue Cars here in Auckland (Carl Barlev’s team) who are experienced in replacing weak cells in battery packs to help extend the car’s life. Hopefully such services will become more cost effective in the next few years. If the car was declining by several bars a year, that would obviously make the range shorter and charges more frequent, which would become a nuisance. At that point. the cost effectiveness of replacing /or tuning up battery packs would become more critical” ● “I think it depends on how easy it will be to replace or recondition the batteries, and at what cost this might be. With any vehicle you expect some maintenance costs and in general EVs are low cost – but investing in new batteries may be acceptable if it is possible and not ridiculously expensive”

Battery replacement is just part of maintenance and repairs: “Aspects of all types of vehicles demonstrate wear, tear and declining functionality. The batteries of electric vehicles are no exception. Battery replacement will become routine” ● “Battery SOH decline is MUCH less significant than wear and tear on an internal combustion engine” ● “I see it as equivalent to wear in an ice engine but doesn’t affect performance or increase pollution just gradually decreasing range. If you use around town and do the average daily kilometres (say 30-40 k’s/day) you might eventually have to charge every night. Horror!!!” ● “If you measure the cost of a battery replacement against the maintenance consumables of an ICE car (cost of service, cam belt, filters, oil change, …), over a period of 10 years maybe battery replacement cost doesn’t look so bad in some cases”

Battery longevity is improving: “One thing is for sure, the problem of battery health in general will fade fast. Battery technology is rapidly improving so they will cost less to replace, will store more energy for a given weight (so the cars will become more efficient) and they will hold their health for longer. EVs that are designed to travel a million km in their lifetime will be commonplace in 10+ years” ● “For those that normally run a car for many years battery health is a definite issue today. Future tech may solve this though, Toyota’s solid-state batteries due in 2022 should last for literally decades” ● “So far it appears that the declining SOH of batteries is happening at a far slower rate than expected. Technology on the other hand is racing ahead, therefore improvements in new battery design, size etc make it worthwhile buying an EV at the earliest opportunity even if it has a lower SOH. The price should reflect that and as the prices drop, EV’s become available to a wider market” ● “Battery technology has advanced to a level where the battery can last longer than the lifetime of an internal combustion engine” ● “The more recent small to medium sized EVs have much greater range to start with and hopefully their batteries will last longer, so the worry about SoH will be much less in future” ● “When a battery is coming to its ‘end-of-life’, range-anxiety will kick in and will eventually trigger a battery replacement cost. Probably a major maintenance cost but hopefully a better-quality battery will be able to be substituted to extend even the original distance on one charge”

Battery replacement will also be an upgrade: “Even if after, say, 10 years, the battery of an EV were to substantially degrade, replacement options should become available which are much more cost-effective than replacements currently available and savings already made in fuel and maintenance costs should more than pay for that replacement. However, due to ongoing battery technology improvements a replacement battery is likely to have much higher capacity than the original, which makes replacement more of an upgrade than simply a replacement”

Battery replacement will be costly: “The replacement of a battery is a significant cost at the time of replacement” ● “Battery replacement is expensive, and the life of the battery has a major impact on the relative fuel costs. If a battery costs $10,000 and has an effective life of 5000 charges of 10 kWh, then the capital/battery cost is 20c per kWh. If the same battery only has an effective life of 2,500 charge cycles then the cost per kWh rises to 40c. When one adds in the actual cost of the electricity (say 20c/kWh) then the ‘fuel’ cost becomes 60c/kWh. On a cost/km basis this is more than half the cost of a petrol-engined small car”

Battery replacement cost is the key: “The price of the battery and the replaceability of it is also very important, perhaps more important than battery lifetime and SOH. Right now, a LEAF battery is about 15k new, or about 4 years of petrol for me. So, the battery just has to last longer than that, but I see how it makes people nervous” ● “I anticipate the battery technology to improve rapidly to a point where, when a SOH looks limiting, replacement becomes relatively cheap and easy to achieve. Recycling of such batteries into other uses seems likely too!” ● “It is essential to know where and who and at what cost you can install a new Battery. Problem is, there are hundreds of car workshops to repair a conventional car, but as relatively new EV owner, I only know one for electric cars and I have no idea if he could exchange the battery in the case of a breakdown” ● “I expect that by the time my battery’s SOH has declined to the point where I will want to do something about it there will be cheaper and higher capacity replacement options that will make my car “better than new” at reasonable cost. In the meantime, I can enjoy all the benefits of EV motoring and have a very low maintenance cost vehicle”

Confusing terminology: “To be honest, I don’t feel that I understand enough about the implications of the battery “state of health” to be able to comment authoritatively. There various terms used in this field which do not make immediate sense to someone who has not fully researched the area. Perhaps it would make more sense to first educate us about the significance of the terminology, in terms of what is already known, research that has been done, etc. Then, we might be in a better situation to answer such a question as the one you posed, which allows very little scope for nuance, or admission of ignorance”

The SOH metrics are poor: “The SoH metric on the Leaf bounces around a lot according to recent charging history, recent travel, and temperature. Fluctuation adds to the emotional roller coaster (yikes when it drops 3 or 4%, yahhh when you regain the percentages). We need better metrics to minimise this erratic fluctuation and better communication to others that it’s only a general guide along the way of a long-term trajectory” ● “The Hx index of internal resistance of the battery to charging is a mystery – it would help if Nissan explained more about how to interpret it”

Some models don’t display SoH: “We don’t know… nothing has changed in the twenty-one months that we have had the Tesla” ● “Many of the models don’t report State of Health, even if the owner would be willing to buy the equipment. I think hiding it makes the anxiety worse – it’s better to know and manage the issue than hide it”

Battery degradation is in-your-face from day one: “It’s a bit worrying to see gradual decline in State of Health (SOH) in particular, even though wear is happening all the time to all parts of any vehicle. But in the EV case the added concern is State of Health’s effect on range, and time delay on longer journeys because you are forced to top-up at a rapid charger more often” ● “I have avoided buying automatic cars in the past due to the high risk and cost when they fail, often enough to write the car off. Most owners bury their heads in the sand with transmissions and only consider its risk when it fails. While autos run, it’s not something you think about and there isn’t a meter constantly telling you that your trans is getting older and closer to blowing up. In EVs the battery health is the high-risk item, but far less risk as the demise is slow and seldom catastrophic. But battery demise is visible (LeafSpy & Guess-o-meters) and is on a range impacting slippery slide from the 1st year. It’s this in-your-face picture of battery health that makes it a concern to owners and EV prospects that wouldn’t think twice about buying an automatic car” ● “The anxiety is always present that as time goes on the instruments show a gradual degradation of the SOH to the point where the range of the vehicle is greatly lessened. The counter to that is eventually to get a new battery pack which will be less of an expense as technology produces less expensive packs”

It’s more a perception issue than real problem: “There are arguments for and against this question. Clearly the battery degradation issue affects EV owners as the already limited range (compared to an ICE) of most EVs available in NZ, decreases over time making certain journey’s difficult or impractical. However, this is more perception than reality for most people as the distance driven on an average day is mostly well within the range of even a degraded battery. So, the best answer I could come up with is to neither agree nor disagree :)” ● “I would not want this thought to put people off turning to EVs!”

It’s an emotional issue: “Our Nissan Leaf (Gen 1 {but with the solar panel}) had 10 bars when we bought it and now has dropped to 9. I was a bit alarmed when yesterday started out newly charged with 114 km on the range, then after about 10 km around town gone down to about 112 km. I THINK we are noticing a more rapid longer drop of the range in the first few km after charging. But we have owned the Leaf for 2 years and 3 months and are still VERY VERY happy with it … that is why i change from strongly agree to agree”

A need for education and more information: “If anyone has information to enlighten us we would be grateful. We fast charge a couple of times a month and then the rest of the time use the slow charger SPARK has installed in Waiwera”

We’re learning as we go: “Too early in life of my vehicle to know” ● “It is too soon to tell whether this is a problem for us in the short time of owning an electric vehicle” ● “Unable to respond definitively because I have no experience of declining SoH as yet” ● “I can’t really answer this question with any knowledge until I get to the end of the battery life so will have to see how it unfolds from here. We own a 2012 Leaf and currently we still have 11 bars for battery health, which seems pretty good” ● “To early to tell. From what I have read and heard depleted battery SOH hasn’t significantly altered the range of a Leaf. In fact, the cars in one fleet with a lower SOH fared better than the new models in the fleet”

It’s important to know what causes different rates of battery degradation: “Monitoring spurs learning about how to look after the battery. Flip the Fleet can do us all a favour by getting the rate of decline in SoH measured and show potential buyers if it really is a problem for the long term financial outcome of EV ownership. Does it decline faster and faster as the car gets older, or does it stabilise? It may take a while to distinguish effects of previous ownership in Japan or UK on SoH compared to NZ conditions, but the regular measures should soon be available from enough Flip the Fleet participants to settle the issue” ● “I was aware that batteries declined over time but did not really understand the significance of that decline caused by quick charging. I only discovered that my vehicle had an unusually high number of quick charges after purchase, which explained my 88% SOH for a car with only 5k on the clock. It has meant that my driving range is reduced but is still adequate for around town where I consistently achieve close to 200 km per home charge” ● “It’s also obvious from the huge individual variation in SoH for a given age or odometer seen in Flip the Fleet’s benchmarking data at http://flipthefleet.org/resources/benchmark-your-leaf-before-buying/ (good stuff folks!) that some people are holding their SOH for way longer than others – we need to pinpoint why and drive an education programme around battery care”

Degradation predictable and manageable: “You can predict it and manage it. It’s not so different from the loss of horsepower over time in most cars. Remember those Top Gear challenges where they bought old performance cars cheaply, and put them on a dynamometer to measure “how many horses have escaped”?” ● “This seems to be entirely manageable” ● “A slow reduction in functionality is not unusual in systems that make our lives better. Easy to plan for and simply part of the ageing process we are all implicated in” ● “Whilst it obviously has some impact on the usability of the car, it’s not significant as it’s quite a gradual decline”

No reason to buy a plug-in hybrid: “A plug-in hybrid is only a compromise – if you have 2 vehicles, get a pure EV!”

Repurpose the battery for house storage: “Hopefully within 5 years in NZ a significant cost of EV battery replacement can be offset by being able to re-purpose the battery as a domestic storage battery where demands in both capacity and power draw are vastly less than in an EV” ● “When degraded beyond usefulness, the battery can be deployed as a house battery” ● “I will still be able to use the vehicle locally even with only 50% SOH. When the battery is too low for local use in my car I intend to add the battery pack to my existing solar system and thereby increase my storage capabilities” ● “It will be a long time before any batteries go onto second life as a fixed battery e.g. at home or commercial use e.g. providing peak time demand for EV Charging perhaps”

Suck it up– it’s more about being environmentally friendly: “I bought my Leaf because of looming climate change, all other issues pale into insignificance compared with that” ● “Obviously, a weakening/ageing battery will have a negative impact on the practicability. However, this is not different to the ageing of other cars, which have more moving parts, requiring more service. A petrol car needs to be fed by more petrol to keep it running, the EV might need a re-sleeving of the battery after some years – the cost might not be much different, and still the EV has a more environmentally friendly impact” ● “In addition, the significant reduction in GHGs is immense and although getting another battery for the car does have environmental impacts, so does digging up all and any fossil fuels! Given that batteries can be reused in other settings (e.g. residential) or recycled (raw materials) the environmental impact is significantly less than the status quo with ICEs” ● “Once a month or so I make trips that push the limits of my range. I foresee easily making these trips becoming less convenient. But, I will not go back to an ICE” ● “Nobody needs an excuse not to buy an EV. The sooner the population of EVs increase, the better for the environment”

It was not a good question: “I don’t find the question very useful” ● “Practicality? No, probably won’t. If the battery degrades to a point nobody wants the vehicle or it is not economically viable to replace the battery then it’s not a good outcome. I have faith that the years of fossil fuel free motoring will pay for the vehicle but I’d have to keep it at least 10-15 years. I think your statement/question is more like 2 or 3 questions” ● “This question is too broad. Lifetime could be 2 or 10 years. Over 2 years it doesn’t matter at all. Over 10 it renders the car useless” ● “Seems like a flawed question. Had a Leaf for a year and it’s very hard to judge if degrading battery is a real issue or not. It’s certainly my biggest concern about the car but it’s also completely hypothetical as we’ve noticed absolutely no difference in our day to day driving. Unsure how you can boil down the difference in perceived impact vs actual impact into a one-click question” ● “It’s hard to know how to score this question because it will vary so much between owners”

Oh, shucks, thanks! “Keep up your great work. I enjoy comparing our vehicle’s performance against others” ● “You are doing a great job. I am a “”data nut”” and keep all sorts of detailed records so I know what a task it can be but also how useful it can be to answer the tricky questions clearly. At 82 I am still a pioneer!